1. Genetic improvement:In the course of an experiment involving brother-sister matings from ddN strain of mice,mice with unusual facial appearance(flat-face)were observed. This flat-face mice always showed complete agenesis of corpus callosum with a frequency of about 0.5 percent. A male or female flat-face mouse was mated to a normal face mouse which resulted in normal face offspring.Matings among these offspring resulted in animals with normal,complete or partial absence of the corpus callosum.Congential agenesis of the corpus callosum observed in the ddN strain mice was classified into two types.The first type was the complete agenesis of corpus callosum.The second type was partial agenesis of corpus callosum, in which genu and splenium corporis callosi were lost, while the truncus part remained intact.Agter fifteen generations of inbreeding,a spontaneous change occurred in one line, resulting in more than 37 percent of adults with agenesis of the corpus callosum.2. Functions of the
… More corpus callosum:Obtained results on the function of corpus callosum in passed three years are as follows.(1).In the acquisition and retention of the avoidance training,there were no difference between congenital acallosal mice and control normal mice.(2).On the other hand,radial maze performance were significantly decreased in congenital acallosal mice and bisection of the anterior part of the corpus callosum.(3).The duration of the electrical stimuli required for stage 3 of the kindling seizer in the anterior corpus callosum bisected group and congenitally acallosal mice were significantly shorter than those in the normal group.(4).The durations of clinical tonic seizure corpus callosum bisected group and congenitial acallosal group were also shorter.(5).However,the time to reach the stage4 were not significantly different.Our results indicate that the anterior part of corpus callosum is an development of the early kindling stage,but is suppresses the manifistation of the clinical tonic seizure. Less